CONSANGUINEOUS AND NEUROTIC INTERMARRIAGE
Byron has sung[109] of the old popular belief in the advantages of
cross-breeding, which arose originally in the practice of exogamy
(marriage outside the tribe), or, more often, outside those having the
same totem, or coat-of-arms. In all probability casual observation of
deformities after intermarriage enforced the prohibition which arose after
the killing of female children had led to exogamy. Totemic relationship
was often far from being consanguineous. The idea of incest is, as Byron's
stanza denotes, of religious origin rather than innate.[110] Its criminal
nature is often removed by priestly dispensation in Latin countries. From
this practice sprang the medical, theologic, and legal notions to which D.
H. Tuke[111] thus refers: "The danger arising from marriages of
consanguinity has been insisted upon from time to time by medical writers,
and has been recognised by ecclesiastical authority, civil law, and by
popular feeling. As regards ecclesiastical and civil law, it would be more
correct to say that the marriage of those very nearly related has been
forbidden on other grounds than that of the alleged danger to mental
health. At the same time the justice of such laws receives support if
medical observation leads to the conclusion that consanguineous marriages
tend to generate idiocy and insanity."
The biologic evidence from the experiments of Maupas on parthenogenesis,
elsewhere cited, is seemingly supported by the results of animals breeding
in-and-in. The evidence advanced against such marriages seems at first
sight exceedingly strong from a biologic standpoint in man.
Rilliet[112] cites cases tending to show that consanguineous marriages, in
themselves pernicious, tend with certainty to lower vital force. The
effects he divides into two categories; those which relate to the
parents, under which head are:--
_a._ Failure of conception.
_b._ Retardation of conception.
_c._ Imperfect conception.
Those which relate to the progeny:--
_a._ Imperfections of various kinds.
_b._ Monstrosities.
_c._ Imperfect physical and mental organisation.
_d._ Tendency to diseases of the nervous system, such as epilepsy,
imbecility, idiocy, deaf-mutism, paralysis, and various cerebral
affections.
_e._ Tendency to strumous diseases.
_f._ Tending to die young.
_g._ Tendency to succumb to disease which others would easily resist.
C. H. S. Davis,[113] of Meriden, Connecticut, states that intermarriages
in families lead to a degeneration that manifests itself in deaf-mutism,
albinism, and idiocy. Isaac Ray[114] is of the opinion that consanguineous
marriages repeated through successive generations account for the numerous
instances of insanity and idiocy occurring in quiet rural populations of
New England, far from the excitements of city life, which are generally
supposed to be more productive of mental unsoundness.
S. M. Bemiss,[115] of New Orleans, Louisiana, giving a report of the
condition of the offspring of 580 intermarriages of first cousins,
gathered mostly by medical men from nearly every State in the Union, says:
2,778 children were born of these cousins, of whom 793 were defective, 117
deaf and dumb, 63 blind, 231 idiotic, 24 insane, 44 epileptic, 189
scrofulous, 53 deformed, and 637 died early.
While these figures seem very demonstrative, they contain a great many
elements of error. One of these is incidentally pointed out by Arthur
Mitchell,[116] who finds that under favourable conditions of life the
apparent ill effects of consanguineous marriages are frequently almost
nil, whilst if the children are ill-fed, badly housed and clothed, the
evil may become very marked. He calculates that the percentage of
consanguineous marriages generally in Scotland is 1.3, or ten times less
than with the parents of idiots. Taking his figures a strong case seems to
be made out in support of the opinion that idiocy, among other evils,
results from intermarriage. Langdon Down, although his figures are not of
so unfavourable a character, admits consanguinity as one of the causes of
deterioration.
George H. Darwin concluded from a careful investigation that about 4 per
cent. of all marriages in England are between first cousins, and between 2
and 3 per cent. in the smaller towns and in the country; with these he
compared the rate of similar marriages among the parents of lunatics and
idiots in asylums, and found it to be about 3 or 4 per cent.--not higher,
therefore, than in the general population.
Huth[117] cites instances occurring regularly at the present day among
certain isolated communities (St. Kilda, Pitcairn, and Iceland) without
apparent evil consequences to the race. Such marriages were common among
the North American Indians and the South Sea Islanders, people among whom
idiocy and other degenerate hereditary conditions were remarkably rare.
These cases, Strahan remarks, deal with peculiarly healthy communities.
Therein lies the secret of such intermarriage proving innocent of evil to
the offspring. Were such intermarriage common among the degenerates the
result would be disastrous.
In 1869 the New York State Medical Society[118] appointed a committee to
investigate the influence of consanguineous marriages upon the offspring.
Their results show clearly that if the family be free from degenerate
taint, marriage among its members in no way diminishes the chances of
healthy offspring. This conclusion is in accord with the findings of
recent investigators like Anstie, George Darwin, and A. H. Huth, according
to whom there is no greater amount of morbidity or abnormality among the
offspring of consanguineous parents than among the children of parents not
so related, provided the parents be equally free from tendency to disease
or degeneration. With a perfectly healthy stock, as every breeder of
animals knows, remarks Strahan,[119] "in-and-in breeding" may be practised
with impunity, but where the stock is tainted with disease or
imperfection, safety is only to be found in "crossing."
Where the error lay in the old doctrine, upon which was founded the
prohibition of consanguineous unions, was not, as Strahan remarks, in
asserting that disease and deformity were more often met with in children
of these than in those of other unions, for such is true, but attributing
these unhappy results to the mere fact that the parents were related by
blood. Over and above the fact that these consanguineous marriages are
almost certain to transmit in an accentuated form any defect or tendency
to disease already present in the family, there is no physiological reason
why such marriages should not take place. Breeders of prize stock
frequently breed "in and in," not only with impunity, but with marked
benefit. But this fact, while going to prove that it is not the mere blood
relationship of the parents which induces the degeneration so often found
in the children of consanguineous marriages, can but rarely be advanced as
an argument in support of the marriage of blood relations. The
stock-raiser only permits the more perfect members of his flocks and herds
to continue their kind, and for this reason the "in-and-in" breeding is
innocuous, just as it would be in the human family under like conditions.
But where shall we find the perfect human family? Such families are
certainly rare. The laws of natural life have been so strained and
perverted that almost every family nowadays has a taint or twist of some
kind, and as all such imperfections are transmitted and rapidly deepened
and fixed in the family by the intermarriage of its members, it is best
that such unions should be forbidden.
Recently acquired characters, whether physiologic or pathologic, are very
liable to disappear when the individual bearing such characters
intermarries with another not having the same character. The natural
tendency in all such cases is to revert in the offspring to the normal or
healthy type, so that unless the new character be very deeply impressed
upon the parental organism it is almost certain it will not appear in the
offspring, if the other parents have nothing of the character. But when
both parents are possessed of the character, whether it be physiologic or
pathologic, this natural tendency to revert to the original is often
overborne and the character is repeated in an accentuated form in the
offspring.
Now this accentuation of all family characters is what must always happen
in the case of consanguineous marriages. If there be any taint in the
family each member of the family will have inherited more or less of it
from the common ancestor. Take the case of cousins, the descendants of a
common grandparent who was insane and of an insane stock. Here the cousins
are certain to have inherited more or less of the insane diathesis. Even
if the taint has been largely diluted in their case by the wise, or, more
likely, fortunate marriages of their blood-related parents, yet will they
have inherited a certain tendency to nervous disease, and if they marry
they must not be surprised if that taint appears in an aggravated form in
their children. Some of the children of such parents are generally
idiotic, epileptic, dumb, or lymphatic, and the parents marvel whence came
the imperfection. It may be in some cases that the parents, and possibly
the grandparent, of the unfortunate children, have not up till that time
displayed any outward evidence of the tendency to disease which they have
inherited and handed on to their descendants; and, not looking farther
back, the parents boldly assert that such a thing as insanity, epilepsy,
scrofula, &c., is unknown to their family. They themselves have never been
insane; why, then, should their children? In like manner children may be
epileptic, blind, deaf-mute, lymphatic, cancerous, criminal, drunkards, or
deformed from direct inheritance, and yet the family line be honestly
declared to be healthy. Hence the truth of Sir William Aitken's maxim,
that "a family history including less than three generations is useless
and may even be misleading." From the foregoing it is evident that the
similarity of temperament induced by a common environment, and which
Strahan would call "social consanguinity," must be a potent factor in the
production of all hereditary degenerations. Living under similar customs,
habits and surroundings, labouring at the same occupation, indulging in
the same dissipation, tend to engender like diseases and degenerations,
irrespective of any blood relationship. Hence it not seldom happens that
persons not even distantly related by blood are, in reality, much more
nearly related in temperament than cousins, or even nearer blood relations
who have experienced widely different modes of life. This "social
consanguinity" is the great curse which dogs every exclusive tribe and
class, and hurries them to extinction. It has largely aided real or family
consanguinity in the production of the diseases and degenerations which
have so heavily fallen upon the aristocracies and royal families of
Europe.
A crucial test of the opposing positions taken respectively in such a
positive manner by Bemiss and Strahan would be a family intermarrying
extensively, but placed under favouring conditions unlikely of themselves
to create degeneracy. Excellent cases of this kind are furnished by
Bourgeois[120] and Thiebault.[121] Bourgeois gives the history of his own
family, which was the issue of a union of the third degree of
consanguinity. During the ensuing 160 years there were ninety-one
marriages, of which sixteen were consanguineous. All of these latter were
productive. There was not a single case of malformation, or other physical
or mental disease in the offspring.
Thiebault reports the case of a slave-dealer who died in the year 1849 at
Whidah, Dahomey, leaving behind him four hundred disconsolate widows, and
about one hundred children. By the order of the king the whole family were
interned in a particular district, where reigned the most complete
promiscuity. In 1863 there were children of the third generation.
Thiebault, after verifying these facts, states that at that time, although
these people were born from all degrees of incestuous unions, there was
not a single instance of deaf-mutism, albinism, blindness, cretinism, or
other congenital malformation. From these cases it is evident that the
position of Strahan is not too strongly taken.
While it is true that "like clings to like," still this does not imply
kinship, but it very often implies likeness in mental characteristics.
This tendency has been shown to be present in the neurotic by Roller,[122]
De Monteyel,[123] Kiernan,[124] Bannister,[125] and Manning,[126] so far
as Germany, France, the United States, and Australia are concerned.
Bannister puts the statistical proof of this tendency very forcibly as
follows: "There are in Illinois, according to the most recent estimates,
in round numbers, about 6,000 insane, or one to a little over 500 of the
population. Even if we double, treble, or quadruple this frequency to
include all that have been or are to be insane, as well as those insane at
the present time, it would not appear that there was much probability of
two insane persons being married according to any ordinary law of chances.
In fact, we find four out of the 104 with insane heredity had both father
and mother insane. In one of these cases the insane heredity involved both
parents and both grandparents on each side, though in the case of the
latter the histories show it only as collateral. Besides these, three
patients had direct paternal and collateral maternal heredity; two had
direct maternal and collateral paternal heredity, and in one case there
was collateral heredity of insanity on both sides. This makes altogether
nearly 10 per cent. of those with insane heredity with it on both sides,
maternal and paternal, and thus favoured with a double opportunity to
inherit mental disease. If we add to this the instances where, with
insanity of one parent, there is reported either epilepsy, hysteria, or
drunkenness, 'brain disease,' nervousness, &c., of the other, the ratio of
double inheritance rises to over 20 per cent."
The beneficial effects which may result from atavism are, it will be
obvious, offset by this tendency of the neurotic to intermarry, thus
perverting the principle of atavism to the assistance of degeneracy.
The age of the parent plays a part in degeneracy. Conger[127] (whose
results have been corroborated by Joseph Workman, of Toronto, and
Kiernan,[128] of Chicago) points out that in all degenerative forms we
must take into consideration this factor, since it determines the
development of degeneracy in childhood. Hereditary taint may be
transmitted to descendants as a simple neuropathy, as a neurosis, or as a
defect of development reaching even to idiocy. Conger finds the prevailing
age, especially the age of the mothers of degenerates, is often between
twenty and twenty-five years, and that hence there exists a relation
between this age and the greater transmission of degeneracy to the
offspring. Marro, who has specially investigated the influence of the age
of the parents, both in the normal population and among criminals,[129]
finds that among all classes of criminals there is an excess of immature
parents (under 26) or senile parents (over 40), and that only petty
offenders possessed a normal number of mature parents (26 to 40 years). A
man between 20 and 25 is in as favourable condition for procreating
degenerates as the very aged. Because of incompleted organic development
he has been unable to free himself from hereditary taint which he
transmits to his descendants, but which in maturer age, through the
influence of adaptation, evolution, or education, might perhaps be more or
less notably modified.
The organism between 20 and 25 is yet incomplete; education has not been
able to exert much influence in determining those possible changes which
are adapted to modify congenital tendencies. In a word, the individual
between 20 and 25 feels too much the influence of atavic characters, and
too readily transmits to his posterity the brands of degeneracy.
Experience has made it well known that the children of the aged readily
show degenerate types. Many children of old fathers have undoubtedly
inherited all the characters of the weakness of the age in which they were
begotten. Old age represents the period of retrogression, of involution,
and hence readily transmits the mark of degeneracy. The children of either
too young or too old parents, failing to escape hereditary predisposition,
may from birth inherit those characters which are proper to incomplete
organic development or to the period of involution.
Kiernan has had under observation a Nova Scotian family of Scotch
extraction, the mother of which continued to bear children until she was
63 years old. There had been no pregnancy between 50 and 56. At 56 a son
was born who had ear, jaw and skull stigmata, and became a periodical
lunatic at 25. A son, born a year after, was a six-fingered idiot, with
retinitis pigmentosa. (These last expressions of degeneracy are, as
Darier[130] has shown, often associated. Darier's cases had the following
hereditary antecedents: One father had hemeralopia; one mother had
defective vision; a grandfather was blind at 30; a grandfather was blind
in one eye, and an uncle had congenital iris coloboma. Only one patient
examined did not have hemeralopic descendants. Six patients examined
belonged to five different families, all consisting of five or six
children, one-third of whom had hemeralopia. Among thirty-five children
there were eleven hemeralopes and two six-fingered children, who died too
young to determine the existence of retinitis pigmentosa. The disease in
all began in childhood, and hemeralopia was absent in but one case.) Three
of the next children (two boys and a girl) became paralytic idiots in
infancy. Here the degeneracy was expressed in that tendency to miliary
aneurismal weakness of arteries to which E. C. Spitzka,[131] called
attention over a decade ago. One of the next children was a periodically
sexual invert female. The last child was an epileptic. The children born
before the age of fifty were normal and averaged 60 years of age.
Matthews Duncan,[132] Arthur Mitchell, and Langdon Down, have called
attention to the influence of premature and late marriage in the
production of idiocy. Factors capable of producing idiocy are of course
capable of producing less decided expressions of degeneracy.